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Abstract:

The apparatus for angular positioning of an operating arm of a tire
changing machine, said arm comprising: a first proximal end hinged to a
column elevating from the base of a tire changing machine such as to
swing in a swinging plane in a first direction of rotation toward a work
position or in an opposite direction of rotation toward a rest position;
an opposite distal end having a support element for supporting work tools
associated therewith; and adjustable lock means for locking rotation in
said first direction of rotation, said apparatus comprising second lock
means for locking rotation of said operating arm in said second direction
of rotation, opposite to said first direction of rotation.

Claims:

1. An apparatus for angular positioning of an operating arm of a tire
changing machine, said arm comprising: A first proximal end hinged to a
column elevating from a base of tire changing machine so as to swing in a
swinging plane in a first rotation direction toward a work position or in
an opposite rotation direction toward a rest position; An opposite distal
end to which a support element of work tools is associated; and
Adjustable locking means of rotations in said first rotation direction,
wherein said apparatus comprises second locking means of rotations of
said operating arm in said second rotation direction opposed to said
first rotation direction.

2. An apparatus according to claim 1, wherein said second locking means
are actuated by automatic actuating means when said work tools reaches
said work position.

3. An apparatus according to claim 1, wherein said second locking means
comprise: at least a stem mounted in a support fixed to said operating
arm and slidable in parallel to said operating arm in said support; an
eccentric arrangement fitted inside said support and alternatively
movable by moving means between a sliding locking position in contact
with said stem and freely sliding position away from said stem.

4. An apparatus according to claim 3, wherein opposing elastic means to
sliding of said stem are interposed between said stem and said support.

5. An apparatus according to claim 3, wherein said stem comprises a first
constant contact end with a corresponding contact point defined on said
column, and a second opposing end.

6. An apparatus according to claim 3, wherein said eccentric arrangement
comprises: a substantially cylindrical element having a prismatic body
having an outer contact surface and a longitudinal axis; a rotating
bracket on which said cylindrical element is mounted and having a
rotation axis parallel to, and eccentric in respect with said
longitudinal axis; an extension of said rotating bracket designed to be
alternatively rotationally handled by an actuating arrangement according
to selected angles; and opposing elastic means to oppose rotations of
said rotating bracket.

7. A tire changing machine comprising an angular positioning apparatus of
an operating arm of a tire changing machine according to claim 1.

Description:

[0001] The invention relates to an apparatus for angular positioning of an
operating arm of a tire changing machine, particularly designed to fix a
predetermined angular position of the operating arm during tire removal
and mounting.

BACKGROUND ART

[0002] Tire changing machines are known to comprise, in short, a base with
a rotatable platform or equivalent device mounted thereto, both known as
a "self-centering unit", defining a generally horizontal plane, upon
which vehicle wheels are laid and locked for tire removal or mounting.

[0003] An upwardly facing column is also provided at one end of the base,
and supports at its upper end a horizontal operating arm which, in turn,
has an adjustable connection device at its free distal end with respect
to the column, for connection of a generally known vertical rod,
hereinafter referred to as "pole", which has at its lower end a connector
for alternative attachment of various work tools, to be used by tire
repairers for removing and mounting tires from and to respective wheel
rims, which tools shall be changed according to the various types of
tires and rims.

[0004] The arm is hinged to the column to swing in a swinging plane, which
is also horizontal, like the plane of the self-centering unit, and move
the pole parallel to itself from a position of non-interference with the
wheel when the latter is locked on the self-centering unit, i.e. away
from the self-centering unit, to a work position on the wheel, i.e.
converging toward the self-centering unit, and vice versa.

[0005] The swinging movements of the arm and the vertical displacements of
the pole relative to the arm toward or away from the self-centering unit
are manually imparted by the tire changer.

[0006] A stop apparatus is also provided between the column and the arm,
for stopping the rotation of the operating arm, when the latter is
rotated toward the self-centering unit to reach the work position.

[0007] This stop apparatus is adjustable for the tire repairer to
precisely lock the rotation of the arm in a predetermined position,
according to the diameter of a wheel, and for the pole to be
substantially aligned with the vertical of a point of the circle in which
an active portion of a work took, namely a hook, has to be introduced,
particularly between the edge of the rim and the tire bead, for hooking
the latter from the inside and extract it from the rim edge, without
damaging the rim or the bead and facilitating the tire repairer's work
even with tires having particularly rigid sidewalls, like in low-profile
tires.

[0008] These work tools have hooks rotatably articulated to a shank,
integral with the pole, for the hooks to be positioned with a proper
orientation using an appropriate pneumatic actuator, which will allow
them to be oriented relative to the profiles of the bead and rim edges
and to move beyond them as they are introduced therebetween and then to
hook the inner edges of the beads during removal thereof from the rims.

[0009] The hook-shaped end of the work tool is introduced between the tire
bead and the rim edge by a thrust exerted on the tire bead, which
progressively overcomes the elastic resistance of the bead, which will
bend inwards from the rim, i.e. towards the coupling channel, and open a
passage for the work tool end which, after overcoming the inner edge of
the bead, rotates about an axis of articulation to the shank and hooks it
when the tire repairer reverses the pole displacement direction, i.e.
pulls the pole out upwards to overcome the rim edge.

[0010] When the hook-shaped tools are forced against a tire bead to bend
it and open the passage between the bead and the rim edge, the latter
receive a back thrust from the sidewall of the tire which opposes
bending.

[0011] This back thrust has a generally oblique direction, which extends
radial to the tire and is transmitted from the hook to the pole and then
from the latter to the operating arm.

[0012] One drawback of the prior art is that a radial component of this
thrust, i.e. parallel to the plane of the self-centering plane will act
upon the pole and hence upon the operating arm which, as a result, will
be pushed back and tend to rotate away from the self-centering unit.

[0013] Although this rotation is of small amplitude, it is undesired
because, if the operating arm, the pole and the work tool mounted to the
pole are displaced together, before starting the removal steps they will
no longer be at the optimal working position that the tire repairer has
defined by operating on the stop apparatus and adjusting it to adapt the
position at which the arm rotation will be stopped as a function of the
wheel diameter and to precisely establish the point at which the work
tool shall be introduced to hook the bead edge and to avoid any damages
to the rim or the structure of the sidewall of the tire itself during
removal.

[0014] Therefore, in the prior art, to obviate this drawback, tire
repairers only oppose their own physical force to reaction displacements
induced by the introduction of work tools between rim edges and tire
beads.

[0015] Therefore, the amount of the reaction force opposed by beads will
make it difficult, or even impossible, to maintain the optimal position
preselected by the stop apparatus.

[0016] It should be recalled for clarity that, in a simplified and
generally preferred embodiment, a stop apparatus comprises a support
bracket, which is fixed in a cantilever fashion to the column and extends
therefrom.

[0017] A threaded hole extends through the bracket and has a matingly
threaded pin transversely engaged therewith, in tightening and loosening
directions, and having an operating end facing toward the column and an
opposite distal end, which is designed to receive a contacting portion of
the operating arm, thereby stopping rotation of the operating arm towards
the self-centering unit.

[0018] The pin tightening or loosening operation will change the desired
position for stopping the rotation of the operating arm towards the
self-centering unit and hence will define the precise location at which
the work tool will be introduced.

OBJECTS OF THE INVENTION

[0019] One object of the invention is to improve the state of the art.

[0020] Another object of the invention is to provide an apparatus for
angular positioning of an operating arm of a tire changer that allows the
operating arm to be positioned at a predetermined location, with the
position being held even when reactions are transmitted from a work tool
to the operating arm during the steps required to remove tires from their
rims.

[0021] Another object of the invention is to provide an apparatus for
angular positioning of an operating arm of a tire changing machine, that
simply, unexpensively and effectively fulfills the intended objects.

[0022] In one aspect the invention relates to an apparatus for angular
positioning of an operating arm of a tire changing machine as defined by
the characteristics of claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further characteristics and advantages of the invention will be
more apparent upon reading of the description of an embodiment of an
apparatus for angular positioning of an operating arm of a tire changing
machine, which is illustrated by way of example and without limitation in
the annexed drawings, in which:

[0024] FIG. 1 is a perspective view of a tire changing machine having
first lock means for locking the rotation of an operating arm;

[0025] FIG. 2 is a schematic, broken-away view of a step of introducing a
work tool between the outer edge of a rim of a wheel locked on a support
and lock device of the tire changing machine of FIG. 1 and the inner edge
of a tire bead;

[0026] FIG. 3 is a top view of the tire changing machine of FIG. 1,
equipped with the apparatus for angular positioning of an operating arm
of a tire changing machine of the invention;

[0027]FIG. 4 and FIG. 5 are enlarged and broken away top views of lock
means for locking the rotation of the operating arm, in the unlocked and
locked states respectively;

[0029] FIG. 7 and FIG. 8 show two diagrams of the fluid-dynamic circuits
for actuating the apparatus for angular positioning of an operating arm
of a tire changing machine of the invention, with the positioning
apparatus being enabled and disabled respectively.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0030] Referring to FIG. 1, the tire changing machine 1 is shown to
comprise a base 2, a vertical column 3 raising upwards from the base 2
and a platform 4 rotatably mounted to the base 2, which is designed to
receive and lock by locking means 5 the wheels "R", from and to which the
tires "P" have to be removed or mounted.

[0031] A substantially horizontal operating arm, referenced 6 and shortly
referred to hereinafter as arm 6, is supported at the upper end of the
column 3 as described below, is adapted to swing, and has an end 103
proximal to the column 3 and an opposite distal end 203.

[0032] The proximal end 103 is hinged to the column 3 by a hinge 7, which
is housed in a support bracket 8 and has a hinge axis "A" substantially
parallel to the column 3, i.e. a substantially vertical axis.

[0033] The opposite end 203 has connector members 9 designed to support a
rod 10, also known as pole and referred to as such hereinafter, which can
slide up and down in a guide sleeve 11 that is part of the connector
members 9, and is manually operated to move towards or away from the
platform 4.

[0034] The lower end 110 of the pole 10 has a connector 13, for mounting
and removal of work tools 14 designed for use by operators to remove or
mount the tires "P" n respective rims "C" of the wheel "R".

[0035] Referring to FIG. 2, a possible work tool 14 is shown in detail,
which comprises a hook element 15 mounted to a support 16 that can be
attached to the connector 13 and that can be introduced between an edge
17 of the rim "C" and a bead "T" of the tire "P", after bending the bead
"T".

[0036] In FIG. 2, the work tool is shown to have the hook 15 articulated
to the support by a parallelogram linkage.

[0037] Here, the articulation between the support 16 and the hook element
14 allows the latter to rotate and automatically adapt to the best
introduction position between the edge 17 and the bead "T".

[0038] As also shown in FIG. 2, the bent bead "T" generates an elastic
reaction force, schematically designated by the arrow "F", which is
directed substantially oblique to the platform 4 and can be resolved into
its two horizontal "F1" and vertical "F2" components, according to the
well-known vector addition rule.

[0039] Referring to FIGS. 1 and 3, it can be seen that first lock means 18
are arranged between the arm 6 and the column 3, for locking rotation of
the arm 6 towards the platform 4.

[0040] The first lock means 18 are adjustable and include a plate 19
extending from the support bracket 8, and having a threaded hole
therethrough for a threaded pin 20 to be screwed therein, the latter
having an operating end with a knob 21, and an opposite free end 120,
which is designed to stop by contact the rotation of the arm 4 towards
the platform 4.

[0041] The free end 120 is received in contact with a pad 22, which is
mounted integral with the outer surface of the arm 6, namely integrally
mounted to a side thereof, the arm 6 having a prismatic section.

[0042] Referring now to FIG. 3, second lock means 23 for locking the
swinging motion of the arm 6 away from the platform 4 are arranged on a
side of the arm 6 opposite to the first lock means 18.

[0043] These second lock means 23 include a rod 24, which is slidably
mounted in a support 25 fixedly associated with the arm 6, e.g. by means
of bolts 125.

[0044] The rod 24 is substantially parallel to the arm 6 and adapted to
slide in the support 25.

[0045] The lock means 23 also include an eccentric assembly 26 arranged in
said support 25 and alternately movable by drive means 27 between a
position in which the sliding motion of the rod 23 is locked and a
position in which the latter is free to slide.

[0046] As shown in FIG. 3, as well as in FIGS. 4 to 7, the drive means 27
also include at least one second linear fluid dynamic actuator 28, whose
shaft 128 has one end restrained by a small arm 29 which is adapted to
rotate in the support 25, by the thrust action of the shaft 128, against
a pressure-loaded spring 30, and about an axis of rotation "B".

[0047] A prismatic body 31 is mounted to the small arm 29 at an end
opposite to the restraint of the shaft 128, which body has a longitudinal
axis "C" parallel to the axis of rotation "B", and eccentric thereto.

[0048] As the small arm 29 rotates, it alternately moves the prismatic
body 31 between a position in contact with the outer surface of the rod
24 and another position away from it, or vice versa.

[0049] In the former case, the sliding motion of the rod 24 is locked, in
the latter it is free.

[0050] More in detail, as shown in FIGS. 6 and 7, the prismatic body 31
has a substantially cylindrical shape, with its ends fitted in special
seats formed in the small arm 29, and a peripheral groove 11 in a
substantially middle area, whose profile matches the outer profile of the
rod 24.

[0051] Referring to FIGS. 8 and 9, there are shown two operating steps of
a fluid dynamic, namely pneumatic, circuit, which actuates both the
rotation of the hook element 15 for introduction or removal, and the
second lock means 23 in a coordinated fashion, i.e. such that, once the
arm 6 is rotated to the selected position, when the operator activates an
actuating control 130 of the actuator 12 which moves the hook element 15
between the bead "T" and the edge 17 of the rim "C", the second lock
means 24 are in an operating state whereas, when the operator activates
the control 130 in reverse mode, i.e. pulls the hook element 15 upwards,
the second lock means 23 will switch their state from operating to idle.

[0052] More in detail, a compressed air source 31 is shown, which is
connected via a feeding port 34, to a distribution valve 32 having two
operating positions, i.e. a position 32A and a position 32B, two
discharge ports 33 and two supply ports 35 and 36.

[0053] The latter are connected to the first fluid dynamic actuator 12 and
the second fluid dynamic actuator 28 respectively, with respective
connecting lines 135 and 136.

[0054] Furthermore, the first fluid dynamic actuator 12 is a double-acting
actuator and has an additional line 137 connected with the line 136.

[0055] As shown in FIG. 8, when the distributing valve 32 is driven into
the work position 32A as shown, the compressed air simultaneously reaches
a thrust chamber 228 of the second linear fluid dynamic actuator 28 and a
return chamber 112 of the first linear actuator 12.

[0056] In this configuration, the respective pistons 328 and 312 move in
the directions of arrows F1 and F2.

[0057] As shown in FIG. 8, a thrust chamber 212 of the first fluid dynamic
actuator 12 is put in a discharge state through the line 135 and the
corresponding discharge port 33.

[0058] In short, the pneumatic configuration of FIG. 8 shows the state in
which the sliding motion of the rod 24 is locked, whereas the reversed
configuration of FIG. 9 shows the state in which the rod 24 is free to
slide.

[0059] Thus, referring to FIG. 9, the work position 32B is shown to
connect the compressed-air source with the thrust chamber 212 of the
first fluid dynamic actuator 12, thereby causing the piston 312 to move
in the direction of arrow F3, whereas the return chamber 112 and the
thrust chamber 228 of the second fluid dynamic actuator 29 are connected
to the discharge port 33.

[0060] Therefore, the piston 328 moves in the direction of arrow F4.

[0061] In order that the rod 24 can be always held in contact with the
column 3, a spring 40 is mounted coaxial to the latter, whose ends are
respectively contained between the support 25 and an abutment washer 41,
which is transversely mounted in the proximity of the end of the rod 24
proximal to the column 3.

[0062] The operation of the invention is as follows: an operator lays a
wheel "R" on the platform 4 and locks it by the locking members 5.

[0063] In this step, the arm 6 is held in a position away from the
platform 4, for easy, interference-free handling of the wheel "R" by the
operator.

[0064] Once the wheel "R" has been locked on the platform 4, the operator
holds the arm 6 and rotates it toward the platform, thereby bringing the
work tool 14, namely the hook element 15, to the vertical line of the
point in which it has to penetrate between the bead "T" of the tire "P"
and the edge 17 of the rim "C".

[0065] Then the operator adjusts the first lock means 18 for the free end
of the threaded pin 20 to contact the lateral surface of the arm 6,
thereby preventing any further rotation thereof toward the platform 4.

[0066] As the operator operates the control 130 (FIG. 8), the distributing
valve 32 will move into the work position 32A and drive simultaneously
the first actuator 12 and the second actuator 28.

[0067] The first actuator 12 will rotate the hook element 15 toward the
wheel "R" and push it between the bead "T" and the edge 17 of the rim
"C", whereas the second actuator 28 will overcome the opposing force of
the spring 30, that will be thus compressed and loaded, and rotate the
small arm 29, thereby moving the prismatic body 31 to contact with the
outer surface of the rod 24, thereby locking its sliding motion relative
to the support 25 (FIG. 5).

[0068] Thus, the rotation of the arm 6 will be prevented in both
directions and the operator-defined position of the arm 6 will be
maintained throughout the step of introducing the hook element 15 between
the bead "T" and the edge 17 of the rim "C".

[0069] Once the hook element 15 has been introduced and the bead "T" has
been automatically hooked thereby, the operator will operate the control
130 (FIG. 9) to move the distributing valve 32 to the work position 32B
and will simultaneously pull back the hook element 15 upwards, thereby
removing the bead "T" from the edge 17 of the rim "C".

[0070] In this configuration, the thrust chamber 228 of the second
actuator 28 is connected to the discharge, and the spring pushes the
piston 328 in a direction opposite to the previous one.

[0071] The shaft 128 will rotate the small arm 29 in such opposite
direction (FIG. 4), and the prismatic body 31 will move away from the rod
24, thereby releasing its sliding motion and allowing the arm 6 to rotate
again away from the platform 4.

[0072] It shall be noted that, as the hook element 15 is so lifted, the
thrust chamber 228 of the second actuator 28 will be emptied more slowly
than the thrust chamber of the first actuator 12, whereby the sliding
motion of the rod 24 will be unlocked with a given delay with respect to
the removal of the bead "T" from the edge 17.

[0073] The above disclosed invention was found to fulfill the intended
objects.

[0074] The invention is susceptible to a number of changes and variants
within the inventive concept.

[0075] Furthermore, all the details may be replaced by other technically
equivalent parts.

[0076] In practice, any materials, shapes and sizes may be used as needed,
without departure from the scope of the following claims.

Patent applications by TECO S.R.L.

Patent applications in class For collapsing or shifting tire axially

Patent applications in all subclasses For collapsing or shifting tire axially